EMUSIC-L Digest Volume 57, Issue 06 This issue's topics: MIDI PIN Connections? (20 messages) Your EMUSIC-L Digest moderator is Joe McMahon . You may subscribe to EMUSIC-L by sending mail to listserv@american.edu with the line "SUB EMUSIC-L your name" as the text. The EMUSIC-L archive is a service of SunSite (sunsite.unc.edu) at the University of North Carolina. ------------------------------------------------------------------------ Date: Tue, 12 Oct 1993 13:22:46 EDT From: Sean Subject: MIDI PIN Connections? Hello all, I would like to make some MIDI cables tonight and was wondering if anyone could tell me which of the five DIN pins I need to hook up. Also, I have enough cable and DIN connectors for tonight but does anyone know a cheap place to order cable and connectors. At Radio Shack's prices it costs more to make the things than to buy a MIDI cable at the local music store. What a rip. Thanks Sean SJEPSON@ERS.BITNET ------------------------------ Date: Tue, 12 Oct 1993 13:45:21 EDT From: ronin Subject: Re: MIDI PIN Connections? wire only the three 'inner' pins, 2, 4, and 5. the other two aren't connected to anything. it's true. in the past few years manufacturing on the things has hit the level where you can get them better and cheaper than you can make them. i only make them when i want to make special cables. mostly cheats like midi y's and runs of 50 feet or more. if you want to make them yourself but keep it cheap you need to bulk order the stuff from someplace like newark electronics. -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 (with Voice Mail) ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ Date: Tue, 12 Oct 1993 13:54:03 EDT From: ronin Subject: Re: MIDI PIN Connections? On Tue, 12 Oct 1993 18:39:37 CET Jack Latanowicz said: > > From what I know to hook up MIDI you need to connect pins 1,2,3 : > 2----------------2 > 4 5 4 5 > ( 1 3 )-------(1-----3) > \---------------/ > And that pin 2 shouldn't be (but may) connected to the masse (metal >cover of the jack). > The other 2 pins theoretically aren't needed. > nope. 2 4 5 1 3 1,3:no connection 2 :shield 4 :power 5 :data -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 (with Voice Mail) ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ Date: Tue, 12 Oct 1993 13:20:21 -0500 From: brickman jonathan Subject: Re: MIDI PIN Connections? Does anyone know how (if it's reasonably easy) to make a MIDI merge box? I priced them awhile back and it was pretty high (80-150$). ||Jonathan E. Brickman brickman@acc.wuacc.edu ------------------------------ Date: Tue, 12 Oct 1993 18:39:37 CET From: Jack Latanowicz Subject: Re: MIDI PIN Connections? On Tue, 12 Oct 1993 13:22:46 EDT Sean said: >Hello all, > >I would like to make some MIDI cables tonight and was wondering if >anyone could tell me which of the five DIN pins I need to hook up. >Also, I have enough cable and DIN connectors for tonight but does anyone >know a cheap place to order cable and connectors. At Radio Shack's prices it >costs more to make the things than to buy a MIDI cable at the local music >store. What a rip. > >Thanks >Sean > >SJEPSON@ERS.BITNET From what I know to hook up MIDI you need to connect pins 1,2,3 : 2----------------2 4 5 4 5 ( 1 3 )-------(1-----3) \---------------/ And that pin 2 shouldn't be (but may) connected to the masse (metal cover of the jack). The other 2 pins theoretically aren't needed. Hope this helps Jack L. ------------------------------------------------------------------------ Jack Latanowicz tel/fax Pl-(0-61) 798-202 Ul.Porzeczkowa 27 Jack@plpuam11.bitnet 61-306 Poznan P O L A N D "exploring life is the sense of living..." ------------------------------------------------------------------------ ------------------------------ Date: Wed, 13 Oct 1993 09:58:44 EDT From: ronin Subject: MIDI PIN Connections? it's a matter of both hardware and software. basically a uart needs to be interfaced with some kind of programmable logic device (think really simple cpu), so that different data streams are 'intelligently' interlaced. data packets have to remain intact and all that sort of thing. there was a diy project for such a beastie in electronic musician a while ago, and i can get you the ref if you really want. but anatek makes one for about $70 that works just fine and doesn't even require power... it draws on the midi line itself. save yourself the hassle. also, if you don't have one already and are now in the process of building any kind of midi system, you're going to want a midi patcher soon. these things are on the order of $300-$400 anyway, and the extra bucks usually pay for functions like merging anyway. so decide where you're actually going with all this before you drop the money on a one-shot black box. -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 (with Voice Mail) ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ Date: Wed, 13 Oct 1993 18:03:28 +0100 From: Nick Rothwell Subject: Re: MIDI PIN Connections? >4 :power >5 :data You mean: "4 & 5: current loop"? I've never ever managed to get my head around this current loop stuff... Anyway: for MY question(s): I want to route MIDI through a stereo patchbay, because I'm building a modular live rig with two small racks. (i) Am I going to have noise problems if I use the PB for MIDI (one end) and audio (other end)? (ii) Is 1/4" stereo jack resilient enough electrically to provide reliable bitwise transmission without dropped signal or introduced noise? (iii) Should the cables be earthed? ISTR that MIDI OUT and MIDI THRU sockets on instruments will deliver earth connection to pin 2/shield, which will generate a loop through the patchbay chassis... Nick Rothwell | cassiel@cassiel.demon.co.uk CASSIEL Contemporary Music/Dance | cassiel@cix.compulink.co.uk ------------------------------ Date: Wed, 13 Oct 1993 12:10:39 -0700 From: Michael O'Hara Subject: Re: MIDI PIN Connections? When building cables with a shield, the best method is to connect the shield at one end only. The end with the shield should (ideally) be connected to the "center point" of the setup (like the patch bay) For unbalanced signals like RCA audio plugs, the best performance is given by using a twisted shielded pair, and using the shield as an actual shield. (that is, hook up one end only, and connect the shield end to the "center point" of the setup if possible. Same goes for 1/4" plugs. Using this method consistently gives 10db improvement in hum and noise pickup. Also remember that the "star" ground arrangement prevents ground loops. So plug everything into ONE large terminal strip if you can. (mains wise) If you can tie all the chassis together, so much the better. (that is, when you mount things in a rack, use toothed or "star" washers of the external variety, and make sure they bite through the paint. ask a simple question, right? :) ------------------------------ Date: Thu, 14 Oct 1993 14:41:56 GMT From: "Bill Purvis, ext 3357" Subject: Re: MIDI PIN Connections? Michael O'Hara wrote: > When building cables with a shield, the best method is to connect the shield > at one end only. For midi cables this is not recommended - the midi spec says that the cable have the shield connected at both ends. BUT the midi-in sockets should NOT have pin 3 (directly) connected. You sometimes see a small capacitor connecting pin 3 to ground, but normally it is left unconnected. If you make your midi cables as described above, you have a 50% chance of not earthing the shield at all (unless you paint one end and always plug that into the midi-out!). Bill ------------------------------ Date: Thu, 14 Oct 1993 14:09:13 EDT From: "I've been stolen by a gypsy. 14-Oct-1993 1402" Subject: Re: MIDI PIN Connections? Nick, I'm sure that 1/4" plugs and jacks are good enough for data. Data is much more robust, electrically speaking than audio. On the other hand, I wouldn't put MIDI and audio in the same patchbay, myself. Maybe for live work only. Think of MIDI as a 5 volt square wave audio signal. It's at least 10 times the level of the audio, and it is current-loop, which is to say that it is running considerably more current than high-impedance audio. I would not like to see MIDI and audio using the same ground because on MIDI gear they are opto-isolated for safety (avoids ground loops). You would probably not have safety problems, but I think you would get at least a tiny amount of zipper noise caused by MIDI data seeping into your audio. I've had that happen when I ran cables parallel for too long a distance, or (I'm certain of this) in the case of my Yamaha piano which has a very high-impedance pickup (read as GOOD ANTENNA). You could probably get away with it for live work, but I don't think it is the right thing to do. Eirikur ------------------------------ Date: Thu, 14 Oct 1993 11:44:04 -0700 From: Michael O'Hara Subject: Re: MIDI PIN Connections? too add just a little to what erikur said.. zipper noise: that is the reason to use that twisted pair cable. So it you must put it in a rack, take the time to build TP cables. And never run data, audio, and power cables together! You are trying very hard to build a coupling transformer when you do that. You can build single racks no prob, but segregate by cable type. also be careful about tapedecks in a rack. Keep em away from large power transformers. try stacking things differently if you get too much hum pickup. too much info. :) ------------------------------ Date: Thu, 14 Oct 1993 12:45:48 -0700 From: Michael O'Hara Subject: Re: MIDI PIN Connections? whoops.. I never knew that! well, there you have it! But funny - I did paint one end and always plug it into the Output (source end always) Take that as more reason to do the same with your audio cables. (And there are real tests that show the S/N improvement for AUDIO cables. I took that to heart and did if with everything!) sheepishly yours, Mike. ------------------------------ Date: Sun, 17 Oct 1993 15:27:08 +0100 From: Nick Rothwell Subject: Re: MIDI PIN Connections? >For unbalanced signals like RCA audio plugs, the best performance is given >by using a twisted shielded pair A twisted shieded pair being what? I'm used to a shielded cable carrying two conductors (not mutually shielded), and I've also come across cable where the individual conductors are shielded, but the resulting cable is usually too thick for the various strain-relief clasps in the connectors. >Also remember that the "star" ground arrangement prevents ground loops. >So plug everything into ONE large terminal strip if you can. (mains wise) I do that on a per-rack basis, but it's not possible with two or more racks. What I've done in the past is have a master power strip, and one mains cable coming off for each rack, plus one for the Apex stand, where each of these units has its own power strip. I've had a fair amount of hum in the past, probably due to flying audio between the racks (mixer FX busses in particular), since that brings in the loop. I broke the shield in a couple of places, which improved things, but finally decided to build a smaller, simpler live rig anyway. >If you can tie all the chassis together, so much the better. A bit tricky: the new CP modular racks are plastic (including the mounting slots). Nick Rothwell | cassiel@cassiel.demon.co.uk CASSIEL Contemporary Music/Dance | cassiel@cix.compulink.co.uk ------------------------------ Date: Sun, 17 Oct 1993 15:27:42 +0100 From: Nick Rothwell Subject: Re: MIDI PIN Connections? >Nick, > I'm sure that 1/4" plugs and jacks are good enough for data. Data is >much more robust, electrically speaking than audio. But it's also much less resilient to errors, especially since MIDI isn't error-corrected. >Think of MIDI as a 5 volt square wave audio signal. It's at least >10 times the level of the audio, and it is current-loop, which is to say that >it is running considerably more current than high-impedance audio. I reckoned as much. I'll try running MIDI at one end of the patchbay and audio at the other, and see what happens. Since the MXR's are "open" patchbays (open PCB's mounted edge-wise into a front panel) I'm wary of the shielding not being very good. I guess, if it doesn't work, it doesn't work (and I look into adding MIDI patchbays as well, but that 2U of every rack used up just for interconnect, and with deep units like the Wavestation A/D in there, it's not possible to mount this stuff on the back). >I would >not like to see MIDI and audio using the same ground because on MIDI gear they >are opto-isolated for safety (avoids ground loops). MIDI is opto-isolated on input only, so it's probably fine to route (grounded) patchbay to MIDI IN, but it's not clear whether MIDI OUT/THRU -> patchbay should be grounded as well, and if so, where. Again, I'll have to experiment. > You could probably get away with it for live work, but I don't think it >is the right thing to do. Neither do I. Anyway, right now I'm mainly interested in getting a live rig, since it has to be neat and portable. Sorting out the recording end of things is easier since physical layout and access isn't quite as constrained. Why does NOBODY make a patchbay that's got audio connectors at one end and MIDI at the other? 1/2U for each. It makes sense to me... Nick Rothwell | cassiel@cassiel.demon.co.uk CASSIEL Contemporary Music/Dance | cassiel@cix.compulink.co.uk ------------------------------ Date: Sun, 17 Oct 1993 15:27:51 +0100 From: Nick Rothwell Subject: Re: MIDI PIN Connections? >zipper noise: that is the reason to use that twisted pair cable. As I've said, I'm not certain I know what you mean by this. >And never run data, audio, and power cables together! You are >trying very hard to build a coupling transformer when you do that. In a 6U rack it's quite difficult to keep them apart. This time I'm going to cut all the cables to length and tie them properly in place to make sure there's nothing coiled up where it shouldn't be, and I'll try to keep audio and MIDI/mains away from each other. A lot of it depends where different rack instruments put their connectors, of course. >too much info. That's not a problem. The problem is all the time it's going to take to try out different combinations and see what works... Nick Rothwell | cassiel@cassiel.demon.co.uk CASSIEL Contemporary Music/Dance | cassiel@cix.compulink.co.uk ------------------------------ Date: Sun, 17 Oct 1993 09:18:31 -0700 From: Michael O'Hara Subject: Re: MIDI PIN Connections? >A twisted shieded pair being what? this is a twisted pair of insulated but unshielded wires, covered with a single common shield. >I broke the shield ina couple of places, which improved things... Well, this is why I hate single ended connections in general. You can do a couple of things here: Connect all the equipment together (the two banks, that is) with #4 wire, to all the chassis. This is only somewhat satisfactory. A better approach is to keep the halves of a setup as seperate as you possibly can, and then use coupling transformers between the two halves. That is to say - keep the two halves seperate, or make them into a grounded monolith, electrically. Yuckky, isn't it? >Plastic chassis Well, within a chassis, use #12 or better wire to connect units together star washers, etc. Of course, if the setup works fine, you don't need to take extreme measures. usually it does, if it is all together, and connected at many points. I prefer metal racks, given a choice. But then I refer to standard 19 inch racks. , ------------------------------ Date: Sun, 17 Oct 1993 09:27:56 -0700 From: Michael O'Hara Subject: Re: MIDI PIN Connections? >zipper noise with badly layed out systems, try rotating a mod wheel. listen for that "buzzing" noise. that is zipper noise. If you have to cross ac and signal wires, cross them at right angles. Just dont run them in parallel for any distance - the magnetic fields couple from one wire to another and in addition to hum, any interference from light dimmers, light switches going on and off, etc will be coupled especially. In fact using a light dimmer on the same breaker as your setup is a good test of your setup. Listen for the "buzzing" produced. ------------------------------ Date: Mon, 18 Oct 1993 12:15:18 CET From: Jack Latanowicz Subject: Re: MIDI PIN Connections? On Sun, 17 Oct 1993 09:27:56 -0700 Michael O'Hara said: >>zipper noise > >with badly layed out systems, try rotating a mod wheel. >listen for that "buzzing" noise. that is zipper noise. > >If you have to cross ac and signal wires, cross them at right angles. >Just dont run them in parallel for any distance - the magnetic fields >couple from one wire to another and in addition to hum, any interference >from light dimmers, light switches going on and off, etc will be coupled >especially. > >In fact using a light dimmer on the same breaker as your setup is a good >test of your setup. Listen for the "buzzing" produced. I cut the zipper noise by plugging MIDI IN on computer interface off while doing playback to the synth. Especially while recording on tape deck music which when is silent , is disturbed by that noise hardly. Jack L. ------------------------------------------------------------------------ Jack Latanowicz tel/fax Pl-(0-61) 798-202 Ul.Porzeczkowa 27 Jack@plpuam11.bitnet 61-306 Poznan P O L A N D "exploring life is the sense of living..." ------------------------------------------------------------------------ ------------------------------ Date: Tue, 19 Oct 1993 23:23:41 +0100 From: Nick Rothwell Subject: Re: MIDI PIN Connections? >this is a twisted pair of insulated but unshielded wires, covered >with a single common shield. OK. Such stuff is actually quite difficult to find here. The two-core cable I've been able to find is either extremely thin, or else far to thick to fit the strain protectors. Right now I'm experimenting with twin shielded cable (think of it as good-quality shielded bellwire) for MIDI. I'll remember to twist it... >A better approach is to keep the halves >of a setup as seperate as you possibly can, and then use coupling >transformers between the two halves. Hmm. The monolith approach sounds easier. At least, I understand what it means... >Well, within a chassis, use #12 or better wire to connect units together >star washers, etc. Most units are earthed (sorry: grounded) so I can use that. >I prefer metal racks, given a choice. But >then I refer to standard 19 inch racks. I'm using CP modular 19" rack cases right now: scandinavian plastic things, which are actually built from sections bolted together using allen keys (so I can knock the 6U racks down to 3U, for instance). The screws mate to square metal nuts held in place by plastic tabs. (It's all quite clever, and the passing similarity to Lego suggests the things are actually Danish.) What all this has to do with electronic music is getting more elusive as we go on... Nick Rothwell | cassiel@cassiel.demon.co.uk CASSIEL Contemporary Music/Dance | cassiel@cix.compulink.co.uk ------------------------------ Date: Tue, 19 Oct 1993 17:15:02 -0700 From: Michael O'Hara Subject: Re: MIDI PIN Connections? earthed = grounded mains = line and you use those funny looking schematics. :) , ------------------------------ End of the EMUSIC-L Digest ******************************